##
## Amazon License Keys
##
#
# Enter a list of valid Amazon license keys. Configure additional keys by
# incrementing the last number. The keys are used following a Round-Robin
# algorithm. This is made available only for personal use. Please see the
# Amazons license at http://www.amazon.com for more information.
#
#amazon.license.0=
#amazon.license.1=
#amazon.license.2=
#amazon.license.3=

Place the above inside portal-ext.properties.

You can get an Amazon License Key here: https://aws-portal.amazon.com/gp/aws/developer/registration/index.html/